Multi-speed transmission

ABSTRACT

A transmission of the present invention has an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices may include clutches and brakes. The torque transmitting devices are selectively engageable in combinations of at least two to establish at least nine forward speed ratios and at least one reverse speed ratio.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices, and more particularly to a transmission havingnine or more speeds, four planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches or brakes, planetary gear arrangements and fixedinterconnections to achieve a plurality of gear ratios. The number andphysical arrangement of the planetary gear sets, generally, are dictatedby packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,four planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices are for example clutches and brakes.

In an aspect of the present invention a transmission is provided havingan input member, an output member, a first, second, third and fourthplanetary gear sets each having sun gears, carrier members and ringgears. The input member is continuously interconnected with the ringgear member of the first planetary gear set, the sun gear member of thesecond planetary gear set, and the sun gear member of the thirdplanetary gear set. The output member is selectively interconnected withthe carrier member of the fourth planetary gear set.

Additionally, a first interconnecting member continuously interconnectsthe ring gear member of the first planetary gear set with sun gearmember of the second planetary gear set, a second interconnecting membercontinuously interconnects the carrier member of the first planetarygear set with the ring gear member of the second planetary gear set, athird interconnecting member continuously interconnects the sun gearmember of the second planetary gear set with the sun gear member of thethird planetary gear set, a fourth interconnecting member continuouslyinterconnects the ring gear member of the second planetary gear set withthe carrier member of the third planetary gear set and a fifthinterconnecting member continuously interconnects the ring gear memberof the third planetary gear set with the sun gear member of the fourthplanetary gear set.

Further, a first torque transmitting device is selectively engageable tointerconnect the input member, the ring gear member of the firstplanetary gear set, sun gear member of the second planetary gear set andthe sun gear member of the third planetary gear set with the ring gearmember of the fourth planetary gear set, a second torque transmittingdevice is selectively engageable to interconnect the carrier member ofthe second planetary gear set with the carrier member of the fourthplanetary gear set and the output member, a third torque transmittingdevice is selectively engageable to interconnect the carrier member ofthe first planetary gear set, the carrier member of the third planetarygear set and the ring gear member of the second planetary gear set withthe stationary member, a fourth torque transmitting device isselectively engageable to interconnect the sun gear member of the firstplanetary gear set with the stationary member, a fifth torquetransmitting device is selectively engageable to interconnect the ringgear member of the fourth planetary gear set with the stationary member,and a sixth torque transmitting device is selectively engageable tointerconnect the ring gear member of the third planetary gear set andthe sun gear member of the fourth planetary gear set with the stationarymember. The torque transmitting devices are selectively engageable incombinations of at least two to establish at least nine forward speedratios and at least one reverse speed ratio between the input member andthe output member.

It is thus an object of the present invention to provide a transmissionhaving four planetary gear sets.

It is a further object of the present invention to provide atransmission having nine forward speeds and at least one reverse.

It is a still further object of the present invention to provide atransmission having four planetary gear sets, a plurality of couplingmembers and a plurality of torque transmitting devices.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of a nine speed transmissionaccording to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of a nine speedtransmission according to the present invention; and

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that in the particular exampleprovided, the nine speed automatic transmission of the present inventionhas an arrangement of permanent mechanical connections between theelements of the four planetary gear sets. A first component or elementof a first planetary gear set is permanently coupled to a firstcomponent or element of a third planetary gear set. A second componentor element of the first planetary gear set is permanently coupled to asecond component or element of a third planetary gear set. A firstcomponent or element of the second planetary gear set is permanentlycoupled to a first component or element of a third planetary gear set. Athird component or element of the second planetary gear set ispermanently coupled to a second component or element of a thirdplanetary gear set. Finally, a third component or element of the thirdplanetary gear set is permanently coupled to a third component orelement of a fourth planetary gear set.

Referring now to FIG. 1, an embodiment of a nine speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear set are each represented by a node. Therefore, a single levercontains three nodes: one for the sun gear, one for the planet gearcarrier, and one for the ring gear. The relative length between thenodes of each lever can be used to represent the ring-to-sun ratio ofeach respective gear set. These lever ratios, in turn, are used to varythe gear ratios of the transmission in order to achieve appropriateratios and ratio progression. Mechanical couplings or interconnectionsbetween the nodes of the various planetary gear sets are illustrated bythin, horizontal lines and torque transmitting devices such as clutchesand brakes are presented as interleaved fingers. If the device is abrake, one set of the fingers is grounded. Further explanation of theformat, purpose and use of lever diagrams can be found in SAE Paper810102, “The Lever Analogy: A New Tool in Transmission Analysis” byBenford and Leising which is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a fourth planetary gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C and an output shaft or member 22.

The input member 12 is coupled to the first node 14A of the firstplanetary gear set 14. The first node 14A of the first planetary gearset 14 is coupled to the first node 18A of the third planetary gear set18. The second node 14B of the first planetary gear set 14 is coupled tothe second node 18B of the third planetary gear set 18. The first node16A of the second planetary gear set 16 is coupled to the first node 18Aof the third planetary gear set 18. The third node 16C of the secondplanetary gear set 16 is coupled to the second node 18B of the thirdplanetary gear set 18. The third node 18C of the third planetary gearset 18 is coupled to the third node 20C of the fourth planetary gear set20. The output member 22 is coupled to the first node 20A of the fourthplanetary gear set 20.

A first clutch 26 selectively connects the first node 14A of the firstplanetary gear set 14 and the input member 12 with the second node 20Bof the fourth planetary gear set 20. A second clutch 28 selectivelyconnects the second node 16B of the second planetary gear set 16 withthe first node 20A of the fourth planetary gear set 20 and the outputmember 22. A first brake 30 selectively connects the second node 14B ofthe first planetary gear set 14, the third node 16C of the secondplanetary gear set 16 and the second node 18B of the third planetarygear set 18 with a stationary element or a transmission housing 50. Asecond brake 32 selectively connects the third node 14C of the firstplanetary gear set 14 with a stationary element or a transmissionhousing 50. A third brake 34 selectively connects the second node 20B ofthe fourth planetary gear set 20 with a stationary element or atransmission housing 50. A fourth brake 36 selectively connects thethird node 18C of the third planetary gear set 18 and the third node 20Cof the fourth planetary gear set 20 with the stationary element or thetransmission housing 50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the nine speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches, brakes, and couplings arecorrespondingly presented whereas the nodes of the planetary gear setsnow appear as components of planetary gear sets such as sun gears, ringgears, planet gears and planet gear carriers.

For example, the planetary gear set 14 includes a sun gear member 14C, aring gear member 14A and a planet gear carrier member 14B that rotatablysupports a set of planet gears 14D (only one of which is shown). Theplanet gears 14D are each configured to intermesh with both the sun gearmember 14C and the ring gear member 14A. The sun gear member 14C isconnected for common rotation with a first shaft or interconnectingmember 42. The ring gear member 14A is connected for common rotationwith the input member 12 and with a second shaft or interconnectingmember 44. The planet carrier member 14B is connected for commonrotation with for common rotation with a third shaft or interconnectingmember 46.

The planetary gear set 16 includes a sun gear member 16A, a ring gearmember 16C and a planet gear carrier member 16B that rotatably supportsa set of planet gears 16D (only one of which is shown). The planet gears16D are each configured to intermesh with both the sun gear member 16Aand the ring gear member 16C. The sun gear member 16A is connected forcommon rotation with a fourth shaft or interconnecting member 48 andwith the second shaft or interconnecting member 44. The ring gear member16C is connected for common rotation with a fifth shaft orinterconnecting member 52. The planet carrier member 16B is connectedfor common rotation with a sixth shaft or interconnecting member 54.

The planetary gear set 18 includes a sun gear member 18A, a ring gearmember 18C and a planet gear carrier member 18B that rotatably supportsa set of planet gears 18D (only one of which is shown). The set ofplanet gears 18D are each configured to intermesh with both the sun gearmember 18A and the ring gear member 18C. The sun gear member 18A isconnected for common rotation with the fourth shaft or interconnectingmember 48. The ring gear member 18C is connected for common rotationwith a seventh shaft or interconnecting member 56. The planet carriermember 18B is connected for common rotation with the fifth shaft orinterconnecting member 52 and the third shaft or interconnecting member46.

The planetary gear set 20 includes a sun gear member 20C, a ring gearmember 20B and a planet gear carrier member 20A that rotatably supportsa first set of planet gears 20D (only one of which is shown) and asecond set of planet gears 20E (only one of which is shown). The firstset of planet gears 20D are each configured to intermesh with both thesun gear member 20C and the second set of planet gears 20E. The secondset of planet gears 20E are each configured to intermesh with both thering gear member 20B and the first set of planet gears 20D. The sun gearmember 20C is connected for common rotation with an eighth shaft orinterconnecting member 58 and the seventh shaft or interconnectingmember 56. The ring gear member 20B is connected for common rotationwith a ninth shaft or interconnecting member 60. The planet carriermember 20A is connected for common rotation with a tenth shaft orinterconnecting member 62 and output member 22.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 22 is continuously connected with the final drive unitor transfer case (not shown).

The torque-transmitting mechanisms or the clutches 26, 28 and the brakes30, 32, 34 and 36 allow for selective interconnection of the shafts orinterconnecting members, members of the planetary gear sets and thehousing. For example, the first clutch 26 is selectively engageable toconnect the input shaft or member 12, the second shaft orinterconnecting member 44 and the ring gear member 14A of the firstplanetary gear set 14 with the ninth shaft or interconnecting member 60.The second clutch 28 is selectively engageable to connect the sixthshaft or interconnecting member 54 with the tenth shaft orinterconnecting member 62. The first brake 30 is selectively engageableto connect the third shaft or interconnecting member 46 with astationary element or the transmission housing 50 in order to preventthe third shaft or interconnecting member 46 from rotating relative tothe transmission housing 50. The second brake 32 is selectivelyengageable to connect the second shaft or interconnecting member 42 witha stationary element or the transmission housing 50 in order to preventthe second shaft or interconnecting member 42 from rotating relative tothe transmission housing 50. The third brake 34 is selectivelyengageable to connect the ninth shaft or interconnecting member 60 witha stationary element or the transmission housing 50 in order to preventthe ninth shaft or interconnecting member 60 from rotating relative tothe transmission housing 50. The fourth brake 36 is selectivelyengageable to connect the eighth shaft or interconnecting member 58 witha stationary element or the transmission housing 50 in order to preventthe eighth shaft or interconnecting member 58 from rotating relative tothe transmission housing 50.

Referring now to FIGS. 2 and 3, the operation of the embodiment of thenine speed transmission 10 will be described. It will be appreciatedthat the transmission 10 is capable of transmitting torque from theinput shaft or member 12 to the output shaft or member 22 in at leastnine forward speed or torque ratios and at least one reverse speed ortorque ratio with a triple overdrive. Each forward and reverse speed ortorque ratio is attained by engagement of one or more of thetorque-transmitting mechanisms (i.e. first clutch 26, second clutch 28,first brake 30, second brake 32, third brake 34 and fourth brake 36), aswill be explained below. FIG. 3 is a truth table presenting the variouscombinations of torque-transmitting elements that are activated orengaged to achieve the various gear states. Actual numerical gear ratiosof the various gear states are also presented although it should beappreciated that these numerical values are exemplary only and that theymay be adjusted over significant ranges to accommodate variousapplications and operational criteria of the transmission 10. An exampleof the gear ratios that may be obtained using the embodiments of thepresent invention are also shown in FIG. 3. Of course, other gear ratiosare achievable depending on the gear diameter, gear teeth count and gearconfiguration selected.

To establish reverse gear, the second brake 32 and the third brake 34are engaged or activated. The second brake 32 connects the second shaftor interconnecting member 42 with a stationary element or thetransmission housing 50 in order to prevent the second shaft orinterconnecting member 42 from rotating relative to the transmissionhousing 50. The third brake 34 connects the ninth shaft orinterconnecting member 60 with a stationary element or the transmissionhousing 50 in order to prevent the ninth shaft or interconnecting member60 from rotating relative to the transmission housing 50. Likewise, thenine forward ratios are achieved through different combinations ofclutch and brake engagement, as shown in FIG. 3.

It will be appreciated that the foregoing explanation of operation andgear states of the nine speed transmission 10 assumes, first of all,that all the clutches and brakes not specifically referenced in a givengear state are inactive or disengaged and, second of all, that duringgear shifts, i.e., changes of gear state, between at least adjacent gearstates, a clutch or brake engaged or activated in both gear states willremain engaged or activated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members; a first interconnecting member continuouslyinterconnecting the first member of the first planetary gear set withfirst member of the second planetary gear set; a second interconnectingmember continuously interconnecting the second member of the firstplanetary gear set with the second member of the third planetary gearset; a third interconnecting member continuously interconnecting thefirst member of the second planetary gear set with the first member ofthe third planetary gear set; a fourth interconnecting membercontinuously interconnecting the third member of the second planetarygear set with the second member of the third planetary gear set; a fifthinterconnecting member continuously interconnecting the third member ofthe third planetary gear set with the third member of the fourthplanetary gear set; and six torque transmitting devices selectivelyengageable to interconnect one of the first, second, and third memberswith at least one other of the first members, second members, thirdmembers, and a stationary member, and wherein the torque transmittingdevices are selectively engageable in combinations of at least two toestablish at least nine forward speed ratios and at least one reversespeed ratio between the input member and the output member.
 2. Thetransmission of claim 1 wherein a first of the six torque transmittingdevices is selectively engageable to interconnect the input member, thefirst member of the first planetary gear set, first member of the secondplanetary gear set and the first member of the third planetary gear setwith the second member of the fourth planetary gear set.
 3. Thetransmission of claim 2 wherein a second of the six torque transmittingdevices is selectively engageable to interconnect the second member ofthe second planetary gear set with the first member of the fourthplanetary gear set and the output member.
 4. The transmission of claim 3wherein a third of the six torque transmitting devices is selectivelyengageable to interconnect the second member of the first planetary gearset, the second member of the third planetary gear set and the thirdmember of the second planetary gear set with the stationary member. 5.The transmission of claim 4 wherein a fourth of the six torquetransmitting devices is selectively engageable to interconnect the thirdmember of the first planetary gear set with the stationary member. 6.The transmission of claim 5 wherein a fifth of the six torquetransmitting devices is selectively engageable to interconnect thesecond member of the fourth planetary gear set with the stationarymember.
 7. The transmission of claim 6 wherein a sixth of the six torquetransmitting devices is selectively engageable to interconnect the thirdmember of the third planetary gear set and the third member of thefourth planetary gear set with the stationary member.
 8. Thetransmission of claim 1 wherein the third member of the first planetarygear set, the first member of the second planetary gear set, the firstmember of the third planetary gear set and the third member of thefourth planetary gear set are sun gears, the second member of the firstplanetary gear set, the second member of the second planetary gear set,the second member of the third planetary gear set and the first memberof the fourth planetary gear set are carrier members and the firstmember of the first planetary gear set, third member of the secondplanetary gear set, the third member of the third planetary gear set andthe second member of the fourth planetary gear set are ring gears. 9.The transmission of claim 1 wherein the input member is continuouslyinterconnected with the first member of the first planetary gear set,the first member of the second planetary gear set, and the first memberof the third planetary gear set, and output member is continuouslyinterconnected with the first member of the fourth planetary gear set.10. The transmission of claim 1 wherein four of the six torquetransmitting devices are brakes and two of the six torque transmittingdevices are clutches.
 11. The transmission of claim 1 wherein thestationary member is a transmission housing.
 12. A transmissioncomprising: an input member; an output member; first, second, third andfourth planetary gear sets each having first, second and third members,wherein the input member is continuously interconnected with the firstmember of the first planetary gear set, the first member of the secondplanetary gear set, and the first member of the third planetary gearset, and output member is continuously interconnected with the firstmember of the fourth planetary gear set; a first interconnecting membercontinuously interconnecting the first member of the first planetarygear set with first member of the second planetary gear set; a secondinterconnecting member continuously interconnecting the second member ofthe first planetary gear set with the second member of the thirdplanetary gear set; a third interconnecting member continuouslyinterconnecting the first member of the second planetary gear set withthe first member of the third planetary gear set; a fourthinterconnecting member continuously interconnecting the third member ofthe second planetary gear set with the second member of the thirdplanetary gear set; a fifth interconnecting member continuouslyinterconnecting the third member of the third planetary gear set withthe third member of the fourth planetary gear set; a first torquetransmitting device selectively engageable to interconnect the inputmember, the first member of the first planetary gear set, first memberof the second planetary gear set and the first member of the thirdplanetary gear set with the second member of the fourth planetary gearset; a second torque transmitting device selectively engageable tointerconnect the second member of the second planetary gear set with thefirst member of the fourth planetary gear set and the output member; athird torque transmitting device selectively engageable to interconnectthe second member of the first planetary gear set, the second member ofthe third planetary gear set and the third member of the secondplanetary gear set with the stationary member; a fourth torquetransmitting device selectively engageable to interconnect the thirdmember of the first planetary gear set with the stationary member; afifth torque transmitting device selectively engageable to interconnectthe second member of the fourth planetary gear set with the stationarymember; and a sixth torque transmitting device selectively engageable tointerconnect the third member of the third planetary gear set and thethird member of the fourth planetary gear set with the stationarymember, and wherein the torque transmitting devices are selectivelyengageable in combinations of at least two to establish at least nineforward speed ratios and at least one reverse speed ratio between theinput member and the output member.
 13. The transmission of claim 12wherein the third member of the first planetary gear set, the firstmember of the second planetary gear set, the first member of the thirdplanetary gear set and the third member of the fourth planetary gear setare sun gears, the second member of the first planetary gear set, thesecond member of the second planetary gear set, the second member of thethird planetary gear set and the first member of the fourth planetarygear set are carrier members and the first member of the first planetarygear set, third member of the second planetary gear set, the thirdmember of the third planetary gear set and the second member of thefourth planetary gear set are ring gears.
 14. The transmission of claim12 wherein the stationary member is a transmission housing.
 15. Atransmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having sun gears,carrier members and ring gears, wherein the input member is continuouslyinterconnected with the ring gear member of the first planetary gearset, the sun gear member of the second planetary gear set, and the sungear member of the third planetary gear set, and output member iscontinuously interconnected with the carrier member of the fourthplanetary gear set; a first interconnecting member continuouslyinterconnecting the ring gear member of the first planetary gear setwith sun gear member of the second planetary gear set; a secondinterconnecting member continuously interconnecting the carrier memberof the first planetary gear set with the ring of the second planetarygear set; a third interconnecting member continuously interconnectingthe sun gear member of the second planetary gear set with the sun gearmember of the third planetary gear set; a fourth interconnecting membercontinuously interconnecting the ring gear member of the secondplanetary gear set with the carrier member of the third planetary gearset; a fifth interconnecting member continuously interconnecting thering gear member of the third planetary gear set with the sun gearmember of the fourth planetary gear set; a first torque transmittingdevice selectively engageable to interconnect the input member, the ringgear member of the first planetary gear set, sun gear member of thesecond planetary gear set and the sun gear member of the third planetarygear set with the ring gear member of the fourth planetary gear set; asecond torque transmitting device selectively engageable to interconnectthe carrier member of the second planetary gear set with the carriermember of the fourth planetary gear set and the output member; a thirdtorque transmitting device selectively engageable to interconnect thecarrier member of the first planetary gear set, the carrier member ofthe third planetary gear set and the ring gear member of the secondplanetary gear set with the stationary member; a fourth torquetransmitting device selectively engageable to interconnect the sun gearmember of the first planetary gear set with the stationary member; afifth torque transmitting device selectively engageable to interconnectthe ring gear member of the fourth planetary gear set with thestationary member; and a sixth torque transmitting device selectivelyengageable to interconnect the ring gear member of the third planetarygear set and the sun gear member of the fourth planetary gear set withthe stationary member, and wherein the torque transmitting devices areselectively engageable in combinations of at least two to establish atleast nine forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.
 16. The transmission ofclaim 15 wherein the stationary member is a transmission housing.